Convert CONFIG_SPL_PAD_TO et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_PAD_TO
   CONFIG_SPL_MAX_SIZE
   CONFIG_TPL_PAD_TO
   CONFIG_TPL_MAX_SIZE

Note that we need to make TPL_MAX_SIZE be hex, and so move and convert the
existing places.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/sama5d27_wlsom1_ek_qspiflash_defconfig b/configs/sama5d27_wlsom1_ek_qspiflash_defconfig
index 3bc9558..08fc34e 100644
--- a/configs/sama5d27_wlsom1_ek_qspiflash_defconfig
+++ b/configs/sama5d27_wlsom1_ek_qspiflash_defconfig
@@ -32,6 +32,7 @@
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_MISC_INIT_R=y
+CONFIG_SPL_MAX_SIZE=0x10000
 CONFIG_SPL_DISPLAY_PRINT=y
 # CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR is not set
 CONFIG_SPL_DM_SPI_FLASH=y